Democratic Party of Japan Secretary General Yukio Edano said recent accusations that economic and fiscal policy minister Akira Amari took bribes could lead to far more serious consequences than previous setbacks to the Abe administration.

Amari is under fire over a media report that he and his aides accepted money from a construction company in exchange for helping the firm receive compensation for disputes over land ownership and waste removal at a public works site.

Amari, a core member of Prime Minister Shinzo Abe’s economic policy team who played a central role in negotiating the Trans-Pacific Partnership free trade agreement, said Friday he has done nothing illegal.

In October 2014, Abe saw two of his ministers resign over misreported political funds and allegations of a possible violation of the election law, although the scandals left voter support for the administration largely intact.

“This is different in nature on two points,” Edano said in an interview. “First of all, he is one of the pillars of the government. The impact on the government will be heavy.

“Second of all, no matter how you look at it, this is not the kind of case where procedural errors are to be blamed,” said Edano, who is a lawyer.

Amari’s office said no one was immediately available to comment.

The accusations prompted the DPJ to put together a team of lawmakers to investigate the reported graft, Edano said.

As Abe’s ruling bloc controls both Diet chambers, the opposition camp can’t paralyze parliamentary debate. But by attacking Amari fiercely, they can make the scandal dominate headlines and potentially hurt voter support for Abe ahead of the Upper House election this summer.

On speculation that Abe may call a snap Lower House election to have it on the same day as the Upper House election, Edano said it would not be surprising if Abe called a Lower House vote even earlier.

“Once the budget bill is passed by around the end of March, it could be anytime. We would like to make preparations with such a scenario in our minds,” Edano said.

Opposition parties are in talks to come up with unified candidates to better compete with the Liberal Democratic Party and Komeito. But an early vote could catch the opposition camp ill-prepared.